The third Monday in July is Marine Day (also known as Sea Day and Ocean Day). This is a Japanese national holiday, that praises sea and its bounties.

The holiday of Marine Day was created in 1941 by then-Minister of Communications Shozo Murata to commemorate the voyage of Meiji Emperor in 1876. He made a voyage in an iron steamship Meiji-Maru, constructed in Scotland in 1874. His voyage included a trip around the Tōhoku region (Honshu Island), embarking on a lighthouse boat in Aomori and a brief stop in Hakodate, after that he returned to Yokihama on July 20 of the same year.

Marine Day was celebrated unofficially till 1995, when it was designated a national holiday. The first official celebration of Marine Day took place on July 20, but now there is no fixed day of the holiday. In 2003 this holiday was moved to the first Monday in July, making it the first summer holiday, that falls on a working day. These changes were made by the Happy Monday System legislation, that created a number of three-day weekends.